Electronic timepiece

ABSTRACT

An electronic timepiece having a reference oscillator and a vibrating motor having resonance frequency driven at a frequency synchronized by said resonance frequency, the resonance frequency of said vibrating motor being continuously adjusted by means of a variable condenser electromechancially coupled therewith such that the oscillation of the vibrating motor remains in phase with the reference frequency. The electric energy required for driving the vibrating motor is in this way kept at a minimum. Control of said variable condenser is effected electronically by means of a phase detector controlled by the reference oscillation and the oscillation of the vibrating motor.

United States Patent [191 Berney ELECTRONIC TIMEPIECE [75] Inventor: Jean-Claude Berncy, Lausanne,

Switzerland [731 Assignees: Compagnie des Montres Longines,

Francillon S.A., Berne; Bernad Golay, Lausanne, both of, Switzerland [22] Filed: Mar. 14, 1972 [21] App]. No.: 234,588

Related US. Application Data [63] Continuation of Ser. No. 53,348, July 16, 1970,

abandoned. I

318/133, 331/8, 331/36, 331/116 M, 331/156 [51] Int. Cl. H02k 33/14 [58] Field of Search... .L 318/119, 128, 129,

318/130, 133; 58/23 R, 23 AC, 23 V; 331/8, 28, 36,116 R, 116 M, 156

[111 3,766,454 Oct. 16, 1973 3,021,492 2/1962 Kaufman 331/36 X 3,512,351 5/1970 Shelley et al. 331/116 X 3,249,876 5/1966 Harrison 331/36 X 2,396,224 3/1946 Artzt 331/156 X Primary Examiner-Gerald Goldberg Assistant Examiner-H. Huberfeld AttorneyDwight H. Smiley [57] ABSTRACT An electronic timepiece having a reference oscillator and a vibrating motor having resonance frequency driven at a frequency synchronized by said resonance frequency, the resonance frequency of said vibrating motor being continuously adjusted by means of a variable condenser electromechancially coupled therewith such that the oscillation of the vibrating motor remains in phase with the reference frequency. The electric energy required for driving the vibrating motor is in this way kept at a minimum. Control of said variable condenser is effected electronically by means of a phase detector controlled by the reference [56] References Cited oscillation and the oscillation of the vibrating motor.

UNITED STATES PATENTS 3,648,453 3/1972 Aizawa et a1. 58/23 V 5 Claims, 3 Drawing Figures PAIENTEDum 16 ms FEGZ Q/IBRATING MOTOR VARIABLE CAPACITY FIGB ELECTRONIC TIMEPIECE This application is a continuation under 37 CPR. 1.60 of my application Ser. No. 55,348, filed July 16, 1970, now abandoned without prejudice.

This invention relates to an electronic timepiece having a reference oscillator and at least one vibrating motor including an electro-mechanical transducer. "Motors vibrating at audio-frequency are advantageous for use in electronic timepieces comprising a reference oscillator of relatively high frequency, for instance a quartz oscillator. However, the vibrating motor having a resonance frequency f should oscillate at a frequency at a fixed ratio to the frequency of the reference oscillator, for instance at a reference frequency of f0. The power consumed by the vibrating motor is a function of the difference between f and fo approximately according to the following formula:

mum for f=fo. Even though f may originally be adjusted to f during manufacture of the timepiece, this frequency may change by aging of parts of the motor or under temperature influences. This frequency drift results in an increase of power consumption, this being particularly undesirable in a watch where the available power is very limited.

Therefore, the vibrating motor should not execute a forced oscillation at the reference frequencyfo, but its resonance frequency should continuously be controlled and adjusted to be equal to the reference frequency f0. This invention aims in providing a control system of this type allowing automatic adjustment of the resonance frequency of the vibrating motor to the reference frequency. The timepiece according to this invention is characterized by a phase detector connected for being controlled by a reference oscillation from said oscillator and the oscillation of said vibrating motor, a variable capacity coupled with said vibrating motor and connected to be controlled by the output of said phase detector, the resonance frequency of said vibrating motor being controlled by said capacity and phase detector respectively for maintaining a determined phase relation between the oscillation of the vibrating motor and said reference oscillation.

This invention will now be explained in detail with reference to the accompanying drawing illustrating an embodiment of the invention.

FIG. 1 is a block diagram of the important constituents of the timepiece,

FIGQZ is an equivalent circuit diagram of the vibrating motor and its transducer and FIG. 3 is a circuit diagram showing, by way of example, an embodiment of the electronic control system.

The timepiece schematically illustrated in FIG. 1 has a reference oscillator not shown from which a reference signal at a stable frequency fo is applied to the one input terminal of a phase detector 2 directly or through a frequency divider. The other input terminal of the phase detector 2 is connected to a vibrating motor 1. The output of the frequency detector controls a variable capacity 3 connected in parallel with the coil of the electro-mechanical transducer of the vibrating motor.

The vibrating motor 1 sustained in oscillation by a circuit well known in the art and not shown in FIGS. 1 and 2 produces a sinusoidal voltage across the terminals of its tranducer. This voltage is used for control of the phase detector 2 by which a voltage or current is produced in accordance with the phase between the oscillation of the motor 1 and the oscillation at reference frequency f0. This control voltage determines the value of capacity 3 connected to the terminals of the transducer. The effect of the capacity on the resonance frequency of the motor is explained below with reference to FIG. 2. It may be shown that the vibrating mass of the motor is comparable to a capacity C while the clasticity of the vibrating system is equivalent to an inductivity L and the losses are equivalent to a parallel resistance Rp. The transducer 4 may be considered as a transformer having a ratio of n. If the transducer has a coil displaceable in a magnetic field, as is usual, the ratio n is determined by the induction of the field and the number of turns of the coil, the resistance of the coil being Rb.

It is seen that in this case the capacity 3 is connected in parallel with the equivalent capacity C of the motor. The frequency may be shifted by the capacity 3 (C by a value of ble, it is seen that the resonance frequency of motor 1 is changed without affecting its quality factor orefficiency. The vibrating motor may include one or more vibrating masses and/or one or more transducers without changing the principles of operation explained above.

If the resonance frequency f of motor 1 is too high (f fo), a decrease of phase occurs. The voltage at the output of the phase detector 2 changes in' order to cause an increase of the value of capacity 3. This increase causes a decrease of the resonance frequency f until balancing is obtained (f= f0). If the frequency f is too low (f fo) the phase increases and the value of capacity 3 decreases.

The motor is ilustrated in the practical embodiment of FIG. 3 by its coil 1 having a tapping. This coil is mounted on a vibrating tongue not shown in the drawing and clamped at one end. The coil is displaceable in a magnetic field in a manner well known in the art. The motor characteristics are as follows:

Pv 1 mW Frequency Hz.

Virtual power voltage automatically stabilizes at a peak to peak value I of 2V determined by the operating voltage V.

Whenever a pulse appears at the collector of transistor 6, a transistor 11 rapidly charges a condenser 12. Simultaneously a pulse is applied to the base of a transistor 13 biased through resistor 14. Transistors 13 and 15 form a bistable circuit serving as a phase detector. When transistor 13 turns conducting, transistor 15 also base of transistor 15 is short-circuited and the bistable circuit returns into its non-conducting state.

The duration of conduction of the bistable circuit thus depends on the time interval between control pulses applied from the motor to transistor 13 and pulses of the reference oscillation applied to transistor 16. This time interval depends on the phase between the oscillation of the motor and the oscillation at reference frequency f0. The output pulses of the bistable phase-detecting circuit are integrated through resistor 17, in an RC system formed by condenser 18 and resistor 19. The direct voltage at point 11 of the circuit is higher when longer pulses are applied from the phase detector, that is when the frequency of motor 1 increases, and vice versa. This direct voltage is applied to a semiconductor element 20 having a capacity value variable in function of. the direct potential applied thereto, This variable-capacity element 20 is connected to the tapping of the motor coil 1 by means of a condenser 21 of relatively high capacity. The alternating voltage at the tapping of coil 1 is sufficiently small for not disturbing the direct voltage bias at the variablecapacity element 20.

When the bias voltage at point I increases the value of the element 20 increases (and vice versa) and tends toshift theresonance frequency of the vibrating motor to the correct value equal to the reference frequency foL' he phase detector illustrated in FIG. 3 and described above may also be used if the reference frequency f is a multiple of the resonance frequency f of the motor. This system may thus be used at the same time as a frequency divider.

The change incapacity required for propercorrectionof the resonance frequency of the motor is in the order of a few nanofarads. Varicaps are now available which are suitable for .the purpose. A number of varicaps may be connected in parallel or a number of elements may be integrated on one base of silicium.

instead of the circuitsillustrated by way of example other suitable circuits may be used. Particularly, any other phase-detector'or variable-capacity element may be used.

In the example illustrated in FIG. 3 and described I above, the motor 1 is synchronized indirectly by comparison of the phase and adjustement of the frequency of the motor by means of the variable capacity. However, it is feasible to directly drive the motor by the reference frequency and to control the frequency of the motor such that the phase shift between the oscillation of the motor and the oscillation at reference frequency is always maintained within narrow limits. A paricular advantage of the system as illustrated and described above resides in the fact that the synchronization of the motor may be combined with a division of frequency, that is, the motor may be synchronized with a frequency which is a multiple of its resonance frequency.

1 claim: v

1. An electronic timepiece comprising a terminal connected to a reference oscillator and at least one vibrating motor having a resonance frequency in the audible range and including an electromechanical transducer an amplifier coupled to a terminal of said electromechanical transducer for (1) applying its output current to said electro-mechanical transducer to sustain oscillation of said vibrating motor, for (2) applying charging current to a condenser, and for (3) applying a signal to a phase detector signal at said resonance frequency induced in said transducer by the oscillation of said vibrating motor to a phase detectorand said phase detector being controlled by a reference oscillation from said reference oscillator, and a variable capacity coupled with said transducer and controlled by the output of said phase detector, the resonance frequency-of said vibrating motor being controlled by said capacity and phase detector respectively via said transducer for maintaining a determined phase relation between the oscillation of the vibrating motor and said reference oscillation.

2. A timepiece according to claim 1, wherein said vibrating motor is a resonator in an self-sustained oscillator synchronized by said reference oscillation.

3. A timepiece according to claim 2, wherein said reference frequency applied to the phase detector is a multiple of the frequency of the vibrating motor.

4. A timepiece according to claim 1, wherein said phase detector comprises a bistable circuit connected for control by pulses formed from the voltage at the ter-v minals of said transducer intoone state and by pulses .formed from said reference frequency into another state, the output signal of said phase comparator-being a function of the duration of said onestate of the bistable circuit. i

5. A timepiece according to claim 1, wherein said vibrating motor is directly driven by a signal at said reference frequency, the resonance frequency of the vibrating motor being controlled according to the phase be tween the oscillation of the motor and erence frequency.

the signal at ref-1 v UNITED STATES PATENT OFFICE CERTIFICATE OF I CORRECTION Patent No. 3} 766,454 Dated October 16, 1972 I vent IRAN-CLAUDE BERNEY .It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Heading E A ssigneesfshou'ld be: Compagnie des Montres Longines, Francillon S.A., Saint Imier and Bernagd Go1ay S, Lausanne Switzerland Continuation of Serial No. @348,

'Signed and sealed'this 20th day. of August 197A.

( Attest: v

MCCOY M. GIBSON, JR. I '0. MARSHALL 9mm I Attesting Officer Commissioner of Patents F ORM PO-105O HO -69) USCOMM-DC 603764 69 U.S. GOVERNMENT HUNTING OFFICE I9! 0-366-334 4 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,766,45 v Dated October 16,- 1973 Inve JEAN-CLAUDE BERNEY I It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Heading E Assigneesshould be: Compagnie des Montres Longines, Francillon S.A. Saint Imier and Bernagd Golayfl ,Lausanne Switzerland Continuation of Serial No. 5,348,

Signed and sealed this 20th day of August 197A.

(SEAL) Attest: v I

MCCOY M. GIBSON, JR. c. MARSHALL 3mm Attesting Officer Commissioner of Patents FORM PO-1050 (10-69) I USCOMM-DC scan-Pee t 11.5. GOVERNMENT PRINTING OFFICE "I! O3.I-3Sl 

1. An electronic timepiece comprising a terminal connected to a reference oscillator and at least one vibrating motor having a resonance frequency in the audible range and including an electromechanical transducer an amplifier coupled to a terminal of said electromechanical transducer for (1) applying its output current to said electro-mechanical transducer to sustain oscillation of said vibrating motor, for (2) applying charging cUrrent to a condenser, and for (3) applying a signal to a phase detector signal at said resonance frequency induced in said transducer by the oscillation of said vibrating motor to a phase detector and said phase detector being controlled by a reference oscillation from said reference oscillator, and a variable capacity coupled with said transducer and controlled by the output of said phase detector, the resonance frequency of said vibrating motor being controlled by said capacity and phase detector respectively via said transducer for maintaining a determined phase relation between the oscillation of the vibrating motor and said reference oscillation.
 2. A timepiece according to claim 1, wherein said vibrating motor is a resonator in an self-sustained oscillator synchronized by said reference oscillation.
 3. A timepiece according to claim 2, wherein said reference frequency applied to the phase detector is a multiple of the frequency of the vibrating motor.
 4. A timepiece according to claim 1, wherein said phase detector comprises a bistable circuit connected for control by pulses formed from the voltage at the terminals of said transducer into one state and by pulses formed from said reference frequency into another state, the output signal of said phase comparator being a function of the duration of said one state of the bistable circuit.
 5. A timepiece according to claim 1, wherein said vibrating motor is directly driven by a signal at said reference frequency, the resonance frequency of the vibrating motor being controlled according to the phase between the oscillation of the motor and the signal at reference frequency. 